There exist a number of systems for measurement of the aberrations in the visual system of the eye, and for measurement of the topography of the cornea of the eye. In US Published Patent Application No. 2003/0142271, for “Aberration and Corneal Topography Measurement”, there is described apparatus for measuring with a single device both the aberrations introduced by an eye and the topography of the cornea of the eye. The method includes determining aberrations within a wavefront created by reflecting a beam off the retina of an eye, determining the corneal topography of the eye from a pattern reflected by the cornea, and directing the beam, wavefront, and reflected pattern using a combiner/separator. The apparatus includes a source for generating the beam for producing the wavefront exiting the eye and a first imaging device for receiving the wavefront, and for determining aberrations using a conventional Hartmann-Shack lenslet array, a projector for projecting the pattern onto the cornea for reflection by the cornea and a second imaging device for receiving the reflected pattern to determine corneal topography, and a combiner/separator for directing the beam, wavefront, and reflected pattern.
In U.S. Pat. No. 7,255,442 for “Device for Measuring Aberrations in an Eye-Type System”, there is described a system similar to that described in the above-reference application, but with a number of improvements and in which, inter alia, both the wavefront measurement system and the keratometer measurement system are mounted on one moveable platform.
Other wavefront measurement instruments and methods for measuring ophthalmic aberrations are described in U.S. Pat. Nos. 6,130,419, 6,460,997, 6,550,917, 6,554,429, 6,565,209, 6,736,509, 6,264,328, 5,777,719, 6,827,444, and 7,036,934.
Many of these machines have some drawbacks, whose elimination would make such an instrument more useful and easier to use, and there therefore exists a need for a wavefront measurement system which overcomes at least some of the disadvantages of prior art systems and methods.
The disclosures of each of the publications mentioned in this section and in other sections of the specification, are hereby incorporated by reference, each in its entirety.